AC187 / AC188 Germanium Pair Alternatives

[sarakisof]

Hello folks, i want to replace a pair of AC187/188 germanium transistors in my Philicorda transistor organ. They have to do with the driver stage of the spring reverb.
I have a bulk of NOS Russian MP20A (ΜΠ20Α) = equivalent for AC125 bought from ebay back then for my Farfisa organs and worked well.
Could i use two AC125s to make a 187/188 pair, by swapping legs for NPN 187?

[sarakisof]

If i go silicon what pair could i use? Note that the 187/188 pair uses heatsinks cases, see the pic below. So, according to schemo, what silicon options i have in terms of heating?
BC548/558(200mA), BC337/327(800mA) or other?
And if so, i have to trim bias the R524 right?

Schem page 12: http://www.peel.dk/Philips/Philicorda_GM752_service_manual.pdf

[sarakisof]

Ignore first post. Anyone on second post?

[thetragichero]

when i run into this with old solid state amps in for repair i do a lot of googling
https://www.vintage-radio.net/forum/showthread.php?t=21254 had a pretty good discussion with some ideas

[sarakisof]

Yeap i have read about 6 posts on uk radio forum and another 10 in total. But none for this particular organ schem. Thsts why i asked. I heard thst silicon -probably- would be a good idea, not always ideal though, in therms of current- overheating.
And i see overheating in this organ, they have used from factory heatsinks for those Ge (see pic) and i see R707, R708 in +8 rail overheating, so maybe go silicon isnt good bet.
Thats why i asked if i go with BC337/327 i will be OK?

[duck_arse]

BD139 and BD140. nearly even period correct.

[sarakisof]

Found some BC337/327 laying around, could i use them or i will have bad surprises? 

[sarakisof]

Ok i replaced reverb drive AC187/188 K (heating case package) pair with BC337/327 they seem to get a bit hot after half an hour or so but not so much. Do you think i will have heating issues?
https://alltransistors.com/transistor.php?transistor=22952

Furthemore, i read that you should bias -increase resistor between two bases- if replace Ge with Si pair. What should i do here?

Schem. Page12
http://www.peel.dk/Philips/Philicorda_GM752_service_manual.pdf

[PRR]

> they seem to get a bit hot

If we believe the numbers on the plan, they heat-up with 1.06 Watt. I hope they have heat-tabs. If you can keep a finger on them, they are probably fine.

As long as you can get OK Germanium, why would you switch to Silicon?

If you must, replace bias resistor with two Silicon rectifiers mounted *close*(on) the Silicon power devices.